After the generator starts, the transfer switch transfers load circuits so the generator can power them. When utility source voltage has been restored, the switch re-transfers back to the utility source voltage and the generator then shuts down. Please reference the transfer switch manual for specific information. 1.4 GENERATOR AC CONNECTION SYSTEMS The generator was shipped from the factory with its stator AC output leads connected in a single-phase, 3-wire generator AC connection system (Figure 1.1). The stator assembly in this system consists of a pair of stationary windings, with two leads brought out of each winding. Each single winding can supply 120 VAC, 60 Hertz. When the two windings are connected in series, a 240 VAC, 60 Hertz AC output results. Typically the two “hot” leads in the circuit are Wires No. 11 and 44. The “Neutral” leads are the junction of Wires 22 and 33. Figure 1.1 - Generator AC Connection System 1.5 MAIN CIRCUIT BREAKER The generator’s main circuit breaker is included with the unit as shipped from the factory. The breaker for each unit is described in Figure 1.2. 0 NEUTRAL ! Section 1 - General Information Guardian Liquid-cooled 25 kW Generator Model Rating Phase Actual Current C/B Rating* % over rating Circuit Breaker 005040-2 25,000 W 1 104.2 A 125 A 120% 125A BQ2 * Amp Rating of C/B structured under model. Figure 1.2 - Main Circuit Breaker Generac® Power Systems, Inc. 5 1.6 GENERATOR FUEL SYSTEM This unit has been factory tested and adjusted using a natural gas fuel system. If propane (LP) gas is preferred, refer to Section 1.12, Reconfiguring the Fuel System for LP Vapor. Fuel pressure for a natural gas set up should be five inches to 14 inches of water column (0.18 to 0.5 psi) at all load ranges. Fuel pressure for an LP vapor set up should be 11 inches to 14 inches of water column (0.4 to 0.5 psi) at all load ranges. NOTE: A separate gas line and regulator may be needed to assure proper gas pressure to the generator. Improper gas pressure can cause hard starting and affect engine durability. Gaseous fuels such as natural and LP (propane) gas are highly explosive. Even the slightest spark can ignite such fuels and cause an explosion. No leakage of fuel is permitted. Natural gas, which is lighter than air, tends to collect in high areas. LP gas is heavier than air and tends to settle in low areas. 1.7 ENGINE PROTECTIVE DEVICES The engine has several safety switches which cause the engine to automatically shut down under the following conditions: low oil pressure, high coolant temperature, engine overspeed, low coolant level or overcrank (Figure 1.3). Figure 1.3 - Engine Protective Devices 1.7.1 LOW OIL PRESSURE SWITCH This switch is normally-closed (N.C.) but is held open by engine oil pressure during engine running. Should operating oil pressure drop below about 8-10 psi (55-68 kPa), the switch contacts close and the engine shuts down automatically (Figure 1.4). Figure 1.4 - Low Oil Pressure Switch 1.7.2 HIGH COOLANT TEMPERATURE SWITCH Normally open (N.O.) thermostatic switch has sensing tip which is immersed in captive coolant. Should coolant temperature exceed about 230°F (110°C), the switch contacts close, which causes the engine to shut down automatically (Figure 1.5). Figure 1.5- High Coolant Temperature Switch 1.7.3 LOW COOLANT LEVEL SWITCH Should engine coolant level drop below the level of the high coolant temperature switch, it is possible for the engine to overheat without automatic shutdown. To prevent such overheating without automatic shut down, the engine has a low coolant level sensor. If the engine coolant drops too low, the engine automatically shuts down (Figure 1.6 on page 6). .. .. .. ! Section 1 - General Information Guardian Liquid-cooled 25 kW Generator Section 1 — General Information Guardian Liquid-cooled 25 kW Generator Figure 1.6 - Low Coolant Level Sensor Should AC frequency exceed about 72 Hz, circuit board action will automatically shutdown the engine. • 1.7.5 OVERCRANK SHUTDOWN The engine control board uses a cyclic cranking process when attempting to start the engine. The first crank cycle is a 15-second crank followed by a seven- second rest. This is followed by five more crank cycles each with a seven second crank followed by a seven-second rest. If the engine fails to start after all six attempts, the start attempt is stopped and the overcrank LED turns on. • 1.7.6 LOW BATTERY The engine control board continually monitors the battery voltage and turns on the low battery LED if the battery voltage falls below 12 VDC for one minute. Low battery voltage is a non-latching alarm, which will automatically clear if the battery voltage rises above 12 VDC. • 1.7.7 15A DC FUSE This fuse is located inside the control panel. It protects the panel wiring and components from damaging overload. The unit will not start or crank if the fuse is blown. Replace the fuse with one of the same size, type, and rating. 1.8 UNPACKING • 1.8.1 UNPACKING PRECAUTIONS Han...